Fineline width and line spacing
Chemical etching of a PCB is usually done with ammonium persulfate or ferric chloride. The thickness of standard copper sheets are typically 18 µm or 35 µm. Higher accuracy and fineline etching can be achieved by reducing the copper sheets thickness to 12, 9 or even 6 µm. Keep in mind that in most cases the minimum ratio for manufacturability between copper thickness and linewidth is approximately 1:2. This is because the chemical process leaves the copper closest to the base material wider than the copper farther away. From multiple suppliers, Azitech can etch finelines down to 50 µm.
For volume production in Asia, the fineline limit is currently 60 µm. Our special PCB production partners in Europe can do finelines down to 35 µm. Please contact Azitech’s PCB designers or Field Application Engineers for more information.
| Fineline width and line spacing | EU | Asia |
|---|---|---|
| 9 µm innerlayer | 50 µm | 50 µm |
| 12 µm innerlayer | 50 µm | 66 µm |
| 18 µm innerlayer | 50 µm | 80 µm |
| 35 µm innerlayer | 50 µm | 90 µm |
| 43 µm innerlayer | 100 µm | 100 µm |
| 70 µm innerlayer | 150 µm | 150 µm |
| 105 µm innerlayer | 200 µm | 180 µm |
| 140 µm innerlayer | 250 µm | 225 µm |
| 175 µm innerlayer | 250 µm | 250 µm |
| 210 µm innerlayer | 250 µm | 300 µm |
| Conductor line width and space tolerance | ± 20% | ±- 20% |